1. Field of the Invention
The present invention relates to a method for trimming the exposed lateral edges of printed bound documents conveyed individually or in quires, such as books, brochures or magazines, which are held at the bound lateral edge and brought to a trimming position in a processing plane which is oriented perpendicular to the trimming plane, by way of a translational conveying movement or a conveying movement of a trimming device and a rotational movement.
2. Description of the Related Art
In general, printed documents of the type described above are trimmed to the desired format at the three exposed lateral edges after the signatures forming the documents are bound or after a cover has been applied. It is also possible to trim several superimposed books together without the need for changing the clamping arrangement.
In CH-A-263,992 there is disclosed a so-called trimming device for trimming books and the like, which can be trimmed at three edges in a single clamping operation. For this purpose, a cross-bar which transversely bridges a rotating table, is positioned on a carriage and supported thereon by columns; a threaded nut is guided in the cross-bar. The threaded nut capable of moving vertically, but unable to rotate, supports a threaded spindle and has formed on its bottom side a pressure head for pressing against a pressure plate.
In this published application, there is also described a prior art rotating cutter wherein one or several books or the like are clamped on a rotating table which is supported on a carriage for movement perpendicular to the knife, wherein the three sides of the books are sequentially trimmed with a knife after each rotation of the table by 90.degree..
The embodiment according to the referenced CH-A-263,992 also provides the means for an application using the conventional technology described therein, wherein the rotating table can be rotated in several steps by 360.degree..
A trimming apparatus disclosed in EP-A-0,710,530 for trimming three lateral edges of a bound printed document includes, aside from a knife cooperating with a cutting table, cutting pliers capable of holding a printed document and provided with a positioning mechanism for holding the printed document at the bound edge, wherein the positioning mechanism can be moved translationally and rotationally relative to the knife.
Since the trimming operation is carried out in multiple steps, the trimming devices described above have disadvantages causing an extraordinarily low operating efficiency and hindering automatic loading.
It is thus an object of the present invention to provide a method and an apparatus for carrying out the method which will significantly improve the present operating efficiency while at the same time maintaining a high degree of reliability and quality.